Bought a book and it says when you select an edge and press ctrl+alt+r it creates 2 parallel edges but nothing happens
They've got the default shortcut wrong. It's CtrlShiftR, which creates two loops on either side of the selected loop, interpolated between it and the ones on either side.

You can hit E while sliding the new loops to make them parallel either to the original loop, or the ones which bound it on either side. F flips which. Hitting E again returns to interpolation.